leftContext Property ($`)


RegExp.leftContext

RegExp: Required. The global RegExp object.

The initial value of the leftContext property is an empty string. The value of the leftContext property changes whenever a successful match is made.

Note
The properties of the RegExp object are not available when running in fast mode, the default for JScript. To compile a program from the command line that uses these properties, you must turn off the fast option by using /fast-. It is not safe to turn off the fast option in ASP.NET because of threading issues.

The short form for the leftContext property is $`. The expressions RegExp["$`"] and RegExp.leftContext can be used interchangeably.

The following example illustrates the use of the leftContext property:

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var s; //Declare variable. var re = new RegExp("d(b+)(d)","ig"); //Regular expression pattern. var str = "cdbBdbsbdbdz"; //String to be searched. var arr = re.exec(str); //Perform the search. s = "$1 returns: " + RegExp.$1 + "\n"; s += "$2 returns: " + RegExp.$2 + "\n"; s += "$3 returns: " + RegExp.$3 + "\n"; s += "input returns : " + RegExp.input + "\n"; s += "lastMatch returns: " + RegExp.lastMatch + "\n"; s += "leftContext returns: " + RegExp.leftContext + "\n"; s += "rightContext returns: " + RegExp.rightContext + "\n"; s += "lastParen returns: " + RegExp.lastParen + "\n"; print(s); //Return results.

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var s;                                //Declare variable.
var re = new RegExp("d(b+)(d)","ig"); //Regular expression pattern.
var str = "cdbBdbsbdbdz";             //String to be searched.
var arr = re.exec(str);               //Perform the search.
s = "$1 returns: " + RegExp.$1 + "\n";
s += "$2 returns: " + RegExp.$2 + "\n";
s += "$3 returns: " + RegExp.$3 + "\n";
s += "input returns : " + RegExp.input + "\n";
s += "lastMatch returns: " + RegExp.lastMatch + "\n";
s += "leftContext returns: " + RegExp.leftContext + "\n";
s += "rightContext returns: " + RegExp.rightContext + "\n"; 
s += "lastParen returns: " + RegExp.lastParen + "\n";
print(s);                            //Return results.

After compiling this program with the /fast- option, the output of this program is:

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$1 returns: bB $2 returns: d $3 returns: input returns : cdbBdbsbdbdz lastMatch returns: dbBd leftContext returns: c rightContext returns: bsbdbdz lastParen returns: d

Version 5.5

Applies To:

RegExp Object

Reference

$1...$9 Properties
index Property
input Property ($_)
lastIndex Property
lastMatch Property ($&)
lastParen Property ($+)
rightContext Property ($')

Arguments

Remarks

Example

Requirements

Applies To:

See Also

Reference